Un modelo tridimensional para el análisis de hormigón estructural bajo carga estática creciente hasta la rotura

Este artículo presenta un modelo numérico para el análisis no lineal de estructuras de hormigón bajo carga estática creciente hasta la rotura, cuyas principales características son las siguientes: discretización por elementos finitos tridimensionales, ecuaciones constitutivas frágiles para el hormigón, representación distribuida de la fisuración y proceso incremental de carga y fisuración. A continuación, se analizan tres elementos estructurales de comportamiento experimental conocido. Los análisis de un prisma de hormigón en masa con rotura frágil y de una -viga de hormigón armado con rotura por flexión muestran que las predicciones de carga de rotura son moderadamente sensibles al elemento finito y a la malla adoptados. Finalmente, las predicciones para una viga de hormigón armado con rotura por cortante muestran que los resultados pueden ser muy sensibles al criterio de actualización de propiedades del método iterativo, bien por falta de convergencia o por propagación de mecanismos espurios.This paper presents a numerical model for the non-linear analysis of concrete structures under monotonic loading up to failure, the main features of which are as follows: threedimensional finite element modelling, brittle constitutive law for concrete, smeared modelling of cracking and incremental loading and cracking procedure. Three different structural elements of known experimental performance are analysed. The analyses of a plain concrete prism exhibiting a brittle failure and a reinforced concrete beam failing in flexure show that the predictions of ultiinate loads are rather insensitive to the adopted finite element mesh. Finally, the predictions for a reinforced concrete beam failing in shear show that the results may be very sensitive to the updating strategy of the iterative procedure due to lack of convergence or to divergence caused by propagation of spurious mechanisms.Peer Reviewe

CO2-Optimization Design of Reinforced Concrete Retaining Walls Based on a VNS-Threshold Acceptance Strategy

This paper presents one approach to a methodology to design reinforced concrete cantilever retaining walls for road construction using a hybrid multistart optimization strategic method based on a variable neighborhood search threshold acceptance strategy (VNS-MTAR) algorithm. This algorithm is applied to two objective functions: the embedded carbon dioxide (CO 2) emissions and the economic cost of reinforced concrete walls at different stages of materials production, transportation, and construction. The problem involved 20 design variables: four geometric variables (thickness of the stem and the base slab; toe and heel lengths), four material types, and 12 variables for the reinforcement setup. Results first indicate that embedded emissions and cost are closely related and that more environmentally friendly solutions than the lowest cost solution are available at a cost increment of less than 1.28%. The analysis also indicated that reducing costs by 1 Euro could save up to 2.28%kg in CO 2 emissions. Finally, the cost-optimized walls require approximately 4.8% more concrete than the best environmental ones, which need 1.9% more steel. © 2012 American Society of Civil Engineers.This work was supported by the Generalitat Valenciana (Research Project GV/2010/086) and by the Universitat Politecnica de Valencia (Research Project PAID-06-09). The authors are grateful to the anonymous reviewers for their constructive comments and useful suggestions. The authors are also grateful Dr. Debra Westall for her thorough revision of the manuscript.10000-01-01Yepes Piqueras, V.; Gonzalez Vidosa, F.; Alcalá González, J.; Villalba Izquierdo, P. (2012). CO2-Optimization Design of Reinforced Concrete Retaining Walls Based on a VNS-Threshold Acceptance Strategy. Journal of Computing in Civil Engineering. 26(3):378-386. doi:10.1061/(ASCE)CP.1943-5487.0000140S37838626

Memetic Algorithm Approach to Designing Precast-Prestressed Concrete Road Bridges with Steel Fiber Reinforcement

[EN] This paper describes the influence of steel fiber-reinforcement on the design of cost-optimized, prestressed concrete, precast road bridges, with a double U-shaped crosssection and isostatic spans. A memetic algorithm with variable-depth neighborhood search is applied to the economic cost of these structures at different stages of manufacturing, transportation, and construction. The problem involved 41 discrete design variables for the geometry of the beam and the slab, materials in the two elements, active and passive reinforcement, as well as residual flexural tensile strength corresponding to the fibers. The use of fibers decreases the mean weight of the beam by 1.72% and reduces the number of strands an average of 3.59%, but it increases the passive reinforcement by 8.71% on average, respectively. Finally, despite the higher cost of the fibers, their use is economically feasible since the average relative difference in cost is less than 0.19%.This work was funded by the Spanish Ministry of Science and Innovation (Research Project BIA2011-23602) and the Universitat Politècnica de València (Research Project PAID-06-12).Martí Albiñana, JV.; Yepes Piqueras, V.; González Vidosa, F. (2015). Memetic Algorithm Approach to Designing Precast-Prestressed Concrete Road Bridges with Steel Fiber Reinforcement. Journal of Structural Engineering. 141(2):1-9. https://doi.org/10.1061/(ASCE)ST.1943-541X.0001058S19141

Automatic design of concrete vaults using iterated local search and extreme value estimation

[EN] This paper describes an iterated local search algorithm based on a Gray code global best-descent (ILS-GB) for the automatic design and cost minimization of reinforced concrete vaults for road con-struction. The study involves a vault which measures 12.40 m in horizontal free span, 3.00 m in vertical height of the lateral walls and 1.00 m in earth cover. This problem includes 49 discrete de-sign variables as well as penalty functions for unfeasible solutions. An objective methodology based on the extreme value theory is used to determine the number of experimental tests required to provide a solution with user-defined accuracy as compared to a global optimum solution. Results indicate that the local optima found by ILS-GB fits a three-parameter Weibull distribution so the estimated location parameter γ can be used as an estimation of the global minimum cost solution. The minimum value obtained by ILS-GB differed just 0.81% compared to the theoretical mini-mum value so that, from the structural engineering perspective, the divergence was small enough to be accepted. Finally, the opti-mization method indicates savings of about 7% compared to a traditional design.This study was partially funded by the Spanish Ministry of Science and Innovation (research project BIA2011-23602), as well as the Universitat Politècnica de València (Research Project PAID-06-09). The authors are grateful to Dr. Debra Westall for her thorough revision of the manuscript.Carbonell Lombardero, A.; Yepes, V.; González Vidosa, F. (2012). Automatic design of concrete vaults using iterated local search and extreme value estimation. Latin American Journal of Solids and Structures. 9(6):675-689. http://hdl.handle.net/10251/50651S6756899

Life cycle impact assessment of corrosion preventive designs applied to prestressed concrete bridge decks

[EN] Chloride corrosion of reinforcing steel in concrete structures is a major issue in the construction sector due to economic and environmental reasons. Assuming different prevention strategies in aggressive marine environments results in extending the service life of the exposed structures, reducing the maintenance actions required throughout their operation stage. The aim of the present study is to analyze the environmental implications of several prevention strategies through a life cycle assessment using a prestressed bridge deck as a case study. The environmental impacts of 15 prevention alternatives have been evaluated when applied to a real case of study, namely a bridge deck exposed to a chloride laden surrounding. The Eco-indicator 99 methodology has been adopted for the evaluation of the impacts. As some of the alternatives involve the use of by-products such as fly ash and silica fume, economic allocation has been assumed to evaluate their environmental impacts. Results from the life cycle analysis show that the environmental impacts of the chloride exposed structure can be reduced significantly by considering specific preventive designs, such as adding silica fume to concrete, reducing its water to cement ratio or applying hydrophobic or sealant treatments to its surface. In such scenarios, the damage caused to the environment mainly due to maintenance operations and material consumption can be reduced up to a 30e40% of the life cycle impacts associated to a conventional design. The study shows how the application of life cycle assessment methodologies can be of interest to reduce the environmental impacts derived from the maintenance operations required by bridge decks subjected to aggressive chloride laden environments.The authors acknowledge the financial support of the Spanish Ministry of Economy and Competitiveness, along with FEDER funding (Project: BIA2017-85098-R).Navarro, IJ.; Yepes, V.; Martí Albiñana, JV.; Gonzalez Vidosa, F. (2018). Life cycle impact assessment of corrosion preventive designs applied to prestressed concrete bridge decks. Journal of Cleaner Production. 196:698-713. doi:10.1016/j.jclepro.2018.06.110S69871319

Heuristics in optimal detailed design of precast road bridges

[EN] This paper deals with the cost optimization of road bridges consisting of concrete slabs prepared in situ and two precast-prestressed U-shaped beams of self-compacting concrete. It shows the efficiency of four heuristic algorithms applied to a problem of 59 discrete variables. The four algorithms are the Descent Local Search (DLS), a threshold accepting algorithm with mutation operation (TAMO), the Genetic Algorithm (GA), and the Memetic Algorithm (MA). The heuristic optimization algorithms are applied to a bridge with a span length of 35 m and a width of 12 m. A performance analysis is run for the different heuristics, based on a study of Pareto optimal solutions between execution time and efficiency. The best results were obtained with TAMO for a minimum cost of 104184 euros. Among the key findings of the study, the practical use of these heuristics in real cases stands out. Furthermore, the knowledge gained from the investigation of the algorithms allows a range of values for the design optimization of such structures and pre-dimensioning of the variables to be recommended.The Spanish Ministry of Economy and Competitiveness along with FEDER funding (research project BIA2014-56574-R) financially supported this research. The authors are grateful for the thorough revision of the manuscript by Phillip Zastrow and Francisca Molina-Moreno.Yepes Piqueras, V.; Martí Albiñana, JV.; García Segura, T.; González Vidosa, F. (2017). Heuristics in optimal detailed design of precast road bridges. Archives of Civil and Mechanical Engineering. 17:738-749. https://doi.org/10.1016/j.acme.2017.02.006S738749179

Optimization Design of RC Elevated Water Tanks under Seismic Loads

[EN] This paper deals with the seismic column design of 35 elevated RC water storage tanks. Tanks comprise a top conic trunk reservoir, a column with variable hollow square cross-sections, and a shallow foundation on a sand layer. The five-column heights considered are 20, 25, 30, 35, and 40 m. The five tanks are subjected to seven degrees of seismic loading characterized by the reference peak ground acceleration in Eurocode 8. The elevated tanks are designed against the full prescriptions of Eurocode 2, Eurocode 8, and the Spaniard Structural Code of Practice. This includes variable loads for seismicity, wind, snow, etc., together with the action of self-weight and dead loads. The optimization design method considered is a variant of the old bachelor algorithm, an adaptive threshold acceptance method with a neighborhood move based on the mutation operator from genetic algorithms. Column results show the high nonlinearity of the problem since the horizontal seismic forces depend on the rigidity and height of the columns. The main features of the optimized tanks give guidance for the practical design of this kind of elevated RC water tank.Grant PID2020-117056RB-I00 funded by MCIN/AEI/10.13039/501100011033 and by "ERDF A way of making Europe".Martínez-Martín, FJ.; Yepes, V.; Gonzalez Vidosa, F.; Hospitaler Pérez, A.; Alcalá-González, J. (2022). Optimization Design of RC Elevated Water Tanks under Seismic Loads. Applied Sciences. 12(11):1-19. https://doi.org/10.3390/app12115635119121

Heuristic optimization of RC bridge piers with rectangular hollow sections

This paper deals with the economic optimization of reinforced concrete (RC) bridge piers with hollow rectangular sections and describes the efficiency of three heuristic algorithms: two new variants of the ant colony optimization (ACO) algorithm, the genetic algorithm (GA) and the threshold acceptance (TA) algorithm. The GA and TA are used for comparison with the new ACO algorithms. The total number of variables is 95. All variables are discrete in this analysis. The calibration of the new ACO algorithm recommended a 250-member ant population and 100 stages. The best solution costs 69,467 euros, which means savings of about 33% as compared to experience-based design. Finally, results indicate that the new ACO algorithms are potentially useful for optimizing the costs of real RC structures.This study was funded by the Spanish Ministry of Education (Research Project BIA2006-01444). The authors are grateful for the thorough revision of the manuscript by Dr. Debra Westall.Martínez Martín, FJ.; González Vidosa, F.; Hospitaler Pérez, A.; Yepes Piqueras, V. (2010). Heuristic optimization of RC bridge piers with rectangular hollow sections. Computers and Structures. 88:375-386. https://doi.org/10.1016/j.compstruc.2009.11.009S3753868

Post-stressed constant depth beam concrete road and railway bridge voided decks morphology

[EN] In the work a study to statistically characterise 82 prestressed concrete bridge decks of real flyovers of constant depth are treated. The main objective of the study is to find design formulae with the least number of data so as to improve the preliminary design of this type of structures. The study performs an exploratory analysis and a multivariate analysis of the geometrical variables, the amount of materials and the cost far voided decks. The regression models have allowed predicting the depth of the deck as a function of the span and the externa/ void. The depth is the variable that better explains (51.9%) the cost per unit surface of the deck in road bridges, while for railway decks this variable only explains in the order of 23.4%, what implies more independent variables. The main span and the external void together with the infernal void of the road deck with the number of spa ns and the total length in the case of the railway deck are enough to find the preliminary design of the slab with reasonable accuracy for the economic assessment of the design[ES] En el trabajo se aborda una caracterización estadística de una muestra de 82 tableros reales tipo losa pretensada de canto constante para carreteras y ferrocarriles. El objetivo principal es encontrar fórmulas de predimensionamiento con el mínimo número de datos posible que permita mejorar el diseño previo de estas estructuras.Para ello se ha realizado un análisis exploratorio y otro multivariante de las variables geométricas determinantes, de las cuantías de materiales y del coste de los tableros. Los modelos de regresión han permitido deducir que el canto queda bien explicado por la luz y el aligeramiento exterior. El canto es la variable que mejor explica el coste por unidad de superficie de tablero en losas para carreteras (51,9%), mientras que en las de ferrocarriles sólo lo explica en un 23,4%, por lo que se necesitan más variables para su explicación. La luz principal y los voladizos bastan para el diseño previo de losas para carreteras; si además se incluye el número de vanos y la longitud total, se pueden predimendionar las losas de ferrocarril, con errores razonables en la estimación económica.Los autores agradecen el apoyo de la Universidad Politécnica de Valencia (Proyecto PAID-06-09) y a la Generalitat Valenciana (Proyecto GV/2010/086).Yepes Piqueras, V.; Alcalá González, J.; González Vidosa, F. (2011). Morfología de tableros aligerados de canto constante postesados para puentes carreteros y ferroviarios. Ingeniería civil. (161):61-72. http://hdl.handle.net/10251/50655S617216

Heuristic optimization of reinforced concrete road vault underpasses

[EN] This paper aims at the automatic design and cost minimization of reinforced concrete vaults used in road construction. This paper presents three heuristic optimization methods: the multi-start global best descent local search (MGB), the meta-simulated annealing (SA) and the meta-threshold acceptance (TA). Penalty functions are used for unfeasible solutions. The structure is de¿ned by 49 discrete design variables and the objective function is the cost of the structure. All methods are applied to a vault of 12.40 m of horizontal free span, 3.00 m of vertical height of the lateral walls and 1.00 m of earth cover. This paper presents two original moves of neighborhood search and an algorithm for the calibration of SA-TA algorithms. The MGB algorithm appears to be more ef¿cient than the SA and the TA algorithms in terms of mean results. However, the SA outperforms MGB and TA in terms of best results. The optimization method indicates savings of about 10% with respect to a traditional design. (C) 2011 Elsevier Ltd. All rights reserved.This study was partially funded by the Universidad Politecnica de Valencia (Research Project PAID-06-09) and by the Generalitat Valenciana (Research Project GV/2010/086). The authors are grateful for the thorough revision of the manuscript by Ms. ha Wallon.Carbonell Lombardero, A.; Gonzalez Vidosa, F.; Yepes Piqueras, V. (2011). Heuristic optimization of reinforced concrete road vault underpasses. Advances in Engineering Software. 42(4):151-159. doi:10.1016/j.advengsoft.2011.01.002S15115942